#include <stdio.h>
#include <stdlib.h>

int main()
{  	  		 	 		 
    int i=0, n=0; //1
    float sum = 0;//1

    scanf("%d",&n);//1

    if (n>0){           //1
      for (i=1;i<=n;i++){ //2
                sum += (float)i/(n-i+1);//2
      }
    }
    printf("sum=%.3f",sum);//1
    return 0;//1
}  	  		